Special issue on selected papers from HVDP 2020

High-voltage and discharge plasma technology is playing an increasingly important role in the construction of national economy and social development, and has attracted extensive attention from both academia and industry. As a novel molecular activation method, discharge plasma can enable thermodynamically difficult reactions to occur under relatively mild conditions, and its effectiveness has successfully been demonstrated in gas cleaning and material surface treatment. In recent years, discharge plasma is continuously showing its outstanding performance in energy, medicine, food, agriculture, aerospace industry, etc. However, new challenges have been brought for the theoretical research and technological development of discharge plasma due to the continuous expansion of its application fields. The in-depth research is necessary to unravel basic characteristics, develop diagnostic technologies, and design efficient sources for discharge plasma, and to promote its applications in practice. In the last two years, significant advances of fundamental and applied achievements have been made in the above areas including theory, modeling and numerical simulations, experimental and diagnostic techniques, plasma sources and applications. In this context, the 2020 National Conference on High Voltage and Discharge Plasmas (HVDP 2020) was held in Harbin, China, on October 23-25, 2020, hosted by the Committee of Plasmas and Applications, China Electrotechnical Society, the Division of Plasma Physics in Chinese Physics Society, and the Committee of Plasma Science and Technology, Chinese Society of Theoretical and Applied Mechanics. This event attracted more than 580 participates from 103 universities, research institutes and enterprises all over China. The program included 4 plenary talks, 38 invited talks, 218 oral presentations and 116 poster presentations, which focused discussions on 11 topics including high voltage, pulsed power technology, basic process of plasma, simulation, diagnosis, materials processing and modifications, biomedicine, energy and chemical engineering, aerospace, environment and fusion, as well as two symposiums on linear plasma devices, disinfection, sterilization and protection against COVID-19. This well-established event provides a platform for the attendees to discuss, exchange and present their innovative ideals and latest achievements on discharge plasma and applications. It also benefits from helping young scientists to learn more about discharge plasmas and their potential practical applications, and facilitating interactions and collaborations between academic researchers and potential application users.